ofdm system that supports color adjustment and csk constellation detection

Abstract

The invention provides an OFDM system supporting color adjustment and CSK constellation detection. The OFDM system has the following beneficial effects: 1) the existing PM-CCSK-OFDM scheme is improved, color adjustment is performed on a signal subjected to OOFDM modulation on a sending end to correct the color shift of an optical signal due to the OOFDM modulation process so as to ensure that thelight color required by a user is presented; and 2) unknown parameters are estimated in the presence of the STO of a CSK-OFDM system and in the case that the noise variance is unknown, the type of thetransmitted CSK constellation is accurately identified, and symbol demodulation is performed based on the identified constellation. Therefore, the method provided by the invention can be applied to amulti-target color changing scene.

Description

technical field

[0001] The present invention relates to the technical field of visible light communication, and more specifically, relates to an OFDM system supporting color adjustment and CSK constellation diagram detection. Background technique

[0002] In recent years, visible light communication (Visible Light Communication, VLC) has been widely studied due to its many advantages such as effectively broadening spectrum resources, green energy saving, and high confidentiality [1]. In the VLC system, Color Shift Keying (CSK) is a commonly used modulation technique. The VLC system based on the CSK modulation mode has a higher modulation bandwidth, and thus can realize high-speed signal transmission [2] [3].

[0003] Existing research on CSK is generally carried out from two aspects.

[0004] On the one hand, from the perspective of optimizing the design of the CSK modulation scheme, the spherical algorithm [4] and the interior point method [5] can be used to optimize the ...

Examples

Embodiment 1

[0087] figure 1A schematic diagram of an OFDM system supporting color adjustment and CSK constellation detection provided by the present invention, in which the gray marking module is the invention point of this patent application. The transmitter of the system provided by the present invention can use a pre-specified N in the system for each OFDM symbol based on a certain strategy type One of the CSK constellations is CSK modulated. Therefore, it is necessary to be able to accurately identify the type of the CSK constellation at the receiving end.

[0088] The system provided by the present invention mainly has two processes, namely the color adjustment process and the CSK constellation diagram detection process.

[0089] 1. Color adjustment at the sending end

[0090] After the OOFDM operation, the color balance of the visible light signal will change, and it needs to go through the design and adjustment steps of the present invention to restore it to the preset desired c...

Embodiment 2

[0153] In order to more fully illustrate the beneficial effects of the present invention, the effectiveness and advancement of the present invention will be further described below in combination with the simulation analysis and results of a specific embodiment.

[0154] First, according to the method provided by literature [5], N type =5 kinds of 8-CSK constellation diagrams with different target colors are used as alternative constellation schemes to be sent, and their constellation point coordinates and target color coordinates are listed in Table 1. On the other hand, ACO-OFDM is selected as the OOFDM scheme of this embodiment, and the number of subcarriers is set to N c =64. The simulation system selects a typical indoor room model. The dimension of the room is 4m×4m×3m, and the center of the room is the coordinate origin. It is assumed that the user terminal position coordinates are [0m, 0m, 0.85m]. The VLC channel model adopts the classic ray tracing model [18], and t...

technical field

[0001] The present invention relates to the technical field of visible light communication, and more specifically, relates to an OFDM system supporting color adjustment and CSK constellation diagram detection. Background technique

[0002] In recent years, visible light communication (Visible Light Communication, VLC) has been widely studied due to its many advantages such as effectively broadening spectrum resources, green energy saving, and high confidentiality [1]. In the VLC system, Color Shift Keying (CSK) is a commonly used modulation technique. The VLC system based on the CSK modulation mode has a higher modulation bandwidth, and thus can realize high-speed signal transmission [2] [3].

[0003] Existing research on CSK is generally carried out from two aspects.

[0004] On the one hand, from the perspective of optimizing the design of the CSK modulation scheme, the spherical algorithm [4] and the interior point method [5] can be used to optimize the ...

Examples

Embodiment 1

[0087] figure 1A schematic diagram of an OFDM system supporting color adjustment and CSK constellation detection provided by the present invention, in which the gray marking module is the invention point of this patent application. The transmitter of the system provided by the present invention can use a pre-specified N in the system for each OFDM symbol based on a certain strategy type One of the CSK constellations is CSK modulated. Therefore, it is necessary to be able to accurately identify the type of the CSK constellation at the receiving end.

[0088] The system provided by the present invention mainly has two processes, namely the color adjustment process and the CSK constellation diagram detection process.

[0089] 1. Color adjustment at the sending end

[0090] After the OOFDM operation, the color balance of the visible light signal will change, and it needs to go through the design and adjustment steps of the present invention to restore it to the preset desired c...

Embodiment 2

[0153] In order to more fully illustrate the beneficial effects of the present invention, the effectiveness and advancement of the present invention will be further described below in combination with the simulation analysis and results of a specific embodiment.

[0154] First, according to the method provided by literature [5], N type =5 kinds of 8-CSK constellation diagrams with different target colors are used as alternative constellation schemes to be sent, and their constellation point coordinates and target color coordinates are listed in Table 1. On the other hand, ACO-OFDM is selected as the OOFDM scheme of this embodiment, and the number of subcarriers is set to N c =64. The simulation system selects a typical indoor room model. The dimension of the room is 4m×4m×3m, and the center of the room is the coordinate origin. It is assumed that the user terminal position coordinates are [0m, 0m, 0.85m]. The VLC channel model adopts the classic ray tracing model [18], and t...

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